1. Field of the Invention
The present invention relates to heat exchangers and particularly to a heat exchanger for the recovery of heat from shale ashes in a process for the continuous retorting of oil shale, the ashes incoming as at least two flows under different pressures, the heat exchanger having tubes arranged in a space latticed pattern and serving to conduct the medium that is to be heated or cooled, the ends of the tubes being held in side walls of a frame wherethrough the shale ashes move vertically to the longitudinal direction of the tubes.
2. Description of the Prior Art
A heat exchanger closely bearing on the invention is disclosed in U.S. Pat. No. 3,483,920. The heat exchanger comprises tubes arranged in at least two horizontal side-by-side planes and serving to conduct a fluid for heat exchange. The tubes in one plane are transverse to those of the other plane. The tubes are held at their ends in the side walls of a frame open at two sides transverse to the side walls to form an inlet and outlet for hot shale ashes. The frame is surrounded by a housing having an inlet and outlet, the housing engaging the frame to form with the housing inlet and outlet a flow path for the fluid through the tubes in the side-by-side planes.
The prior-art heat exchanger may be used for cooling shale ashes incoming in one flow as a vertically moving bed. In the case of picking up shale ashes in two stages of a shale retorting system wherein each stage is characterized by different parameters, particularly pressure, a separate exchanger is required for each stage or ashes flow.